1. Field of the Invention
The present invention relates to an electric vehicle, and more particularly to a controlling method for charging the battery of an electric vehicle adapted to determine a charge state of a battery before charging when a battery used as power source for an electric vehicle is charged relative to an anticipated a current is charge up to a charge end time; and the antisipated current is compared with an actual input current for determining of degree of undercharge and for performance of overcharge, thereby determining a progressive state of aging in the battery.
2. Description of the Prior Art
An electric vehicle is generally constructed with a motor (electric motor), a controller, an inverter, a charger, a DC/DC converter and a battery.
The electric vehicle, unlike the gasoline-powered vehicle, utilizes a limited modularized energy in the battery for running a vehicle, such that, when the limited energy of battery is consumed, the battery should be charged by an external power source. A general battery charging method includes a full power mode, a constant current control first mode, a constant current control second mode, a refresh charge control mode for maintaining 100% charge control state and a battery control mode.
A battery discharging method includes a state of charging calculation, a battery fail check, a projection mode and a battery temperature control mode.
Each control mode compensates for battery aging, based on an initially designed value. When an electric vehicle runs fast according to the control method, a problem occurs in defining one cycle of charge and discharge of a battery. Therefore, one cycle of charge and discharge in a battery is defined when the current battery charge state is above 85% charging capacity and over 2 hours of charging time.
Accordingly, as the battery cycle of an electric vehicle progresses, a charged state against an initial capacity is expressed as a predetermined value of capacity decrease.
In other words, the cycling is defined as a factor influencing a battery aging factor and can be expressed as a battery aging factor.
However, there is a problem in the aforementioned definition of cycling in that an internal resistance change in an electric vehicle battery cannot be positively monitored, thereby making it impossible to charge with actually useable energy, such that a running distance of an electric vehicle is soon shortened to thereby decreased vehicle performance.
The present invention solves the aforementioned problems and it is an object of the present invention to provide a controlling method for carrying the battery of an electric vehicle, where a present charge state is measured, in at the initiation of charging a battery of electric vehicle, to calculate an anticipated current per hour up to an end of charging and to determine the degree of undercharge in consideration of present battery aging for overcharging the under charged battery, thereby preventing an early degradation of vehicle performance.
In accordance with the object of the present invention, there is provided a controlling method for battery charge of an electric vehicle, the method comprising the steps of:
measuring a battery charge state before starting battery charging to calculate an anticipated current for charging and to output a control signal for charging a battery according to a predetermined charge control program; PA1 determining when the charge has been completed after the charging is started; by comparing the anticipated charge current with an actual charging current to determine whether the actual charging current is larger than the anticipated charging current if; PA1 terminating charging if it is determined that the actual charged current is larger than the anticipated charge current; PA1 outputting an overcharge control signal if it is determined that the actual charging current is smaller than the anticipated charging current, and comparing whether voltage of the battery is larger than a maximum voltage to calculate a total charged current, and terminating charging after calculating a battery aging progress state, if it is determined that the battery voltage is larger than the maximum voltage; PA1 checking a battery voltage drop if it is determined that the battery voltage is smaller than the maximum voltage to calculate a total charged current, if it is determined that the voltage drop has occurred in order to calculate a battery aging progress state for completion of charging; PA1 comparatively determining whether a temperature rise rate of the charged battery is larger than a randomly established maximum temperature rise reference value, if it is determined that the voltage drop has not occurred in order to calculate a total charged current, if it is determined that the temperature rise rate of the charged battery is larger than the randomly established maximum temperature rise reference value, and to thereby calculate a battery aging progress state for completion of charging; PA1 comparatively determining whether an actual temperature of a charged battery is larger than a randomly established maximum temperature, if it is determined that the temperature rise rate of the charged battery is smaller than the randomly established maximum temperature rise reference value to calculate a total charged current if it is determined in order that the actual temperature of the charged battery is larger than the randomly established maximum temperature, to thereby calculate a battery aging progress state for completion of the charging; PA1 determining whether charged current per hour is larger than a randomly established maximum charged reference current if it is determined that the actual temperature of the charged battery is smaller than the randomly established maximum temperature to calculate a total charged current, if it is determined that the charged current per hour is larger than the randomly established maximum charged reference current, to thereby and to calculate a battery aging progress state for completion of the charging; and PA1 determining that the battery charge is not completed by a battery charge control unit, if it is discriminated that the charged current per hour is smaller than the randomly established maximum charge reference current to output an overcharge control signal for continuously performing the charging.